Bug fixes in Recents

- Making thumbnails invisible until loaded (fixes regression)
- Speed up dismiss animation from menu
- Make the max swipe velocity greater
- Make only the thumbnail and app title long-clickable
- No more click sound when tapping outside the thumbnails to dismiss Recents
- Tweaking color of recents app label text

Change-Id: If7b6cd59e92feb0472eb3ea266733549cb9f4d4b